In a storage apparatus, improvements in the availability and the performance of the system can be achieved by providing pluralities of similar devices, cables, and the like, to give redundancy to control apparatuses that execute access controls between a host and a storing device, paths between the control apparatus and the storing device, and the like, for example.
Furthermore, a storage apparatus provided with multiple control apparatuses, e.g., controller modules (CMs), may include a switch unit for communications among those CMs. A plurality of such switch units may also be provided to give redundancy for improving the availability and the performance of the system, and may be connected to a back panel of a storage apparatus, for example.
Patent Document 1: Japanese Laid-open Patent Publication No. 2004-341982
Patent Document 2: Japanese Laid-open Patent Publication No. 2008-33588    Patent Document 3: Japanese Laid-open Patent Publication No. 2005-122763
In a storage apparatus as described above, because no redundancy is given to a back panel, any failure of the back panel may cause a suspension of operations of the storage apparatus. After power supply to the entire storage apparatus is cut off, replacement of the back panel is done, for example.
As described above, the availability may decrease in a storage apparatus provided with multiple control apparatuses.